1. Field of the Invention
This invention generally relates to composite building materials, and in particular, to a composite building material having an engineered cement-polymer matrix.
2. Description of the Related Art
Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.
Fiber-reinforced composite materials, particularly fiber cement, have become popular for use as a building material. In many instances, fiber cement is preferred over the more conventional materials such as wood, metal, or plastics. When compared to wood, fiber cement has better water resistance and is also less prone to rotting, cracking or splitting. Additionally, unlike metal or vinyl cladding, which is typically sold in fixed colors, fiber cement articles may be painted on-site using any color of a standard acrylic-based exterior paint typically applied on wood.
To extend the service life of paint on fiber cement, it is generally desirable to reduce the moisture absorbed by the fiber cement so as to reduce a negative effect of absorbed moisture on the integrity of the coating. While most paints may appear capable of resisting water ingress, they are still water permeable to a certain extent and their integrity and adhesion to a substrate may be negatively affected by the amount of moisture absorbed by the substrate. In addition, paint is usually not applied to each and every surface of a building article and this may allow moisture to enter the article through uncoated surfaces. Thus, it is highly desirable to apply a sealer or hydrophobic treatment to all exterior sides or surfaces of a building material, particularly to extend the durability of any coating on the building material, such as a fiber reinforced composite material.
While sealers for concrete applications are well known in the art, conventional concrete sealers do not work well with cementitious, gypsum, or other inorganic composite materials containing cellulose, glass, steel or polymeric fibers. Additionally, these conventional sealers typically have high viscosity and tend to form a film on the surface of the composite material. As such, they are intended to be used as a surface treatment only and are not formulated to penetrate into the subsurface layers of the composite material, to effectively fill the subsurface pores and block the pores therein from moisture. Consequently, paint adhesion and long term paint durability on fiber cement is less than optimal.